1. Field of the Invention
This invention relates to a copying machine which is capable of copying on the front and back faces of a copy medium.
2. Description of the Prior Art
Conventional copying machines have generally been of the type which effects copying on one face of each copy medium. However, when a great quantity of copies is to be preserved, the quantity of the copies becomes double that of books or other matter printed on both sides to be copied and this is disadvantageous in terms of the space required to preserve them and the weight of the copies. Also, from the viewpoint of economizing the required material, manpower and running cost, there is a great need for both-face copying machines which are capable of copying on the front and back faces of each copy medium.
For example, several forms of the image transfer type copying machine capable of both-face copying have heretofore been proposed. One of them is such that ordinary copying (image transfer and fixation) is effected on one face of the copy medium (this will hereinafter be called front-face copying and the course involved therefor will be called the front-face copying course), whereafter such copy medium having completed the single-face copying is guided back to the initial feed means or to second feed means, where the copy medium is reversed and again fed into the copying machine to effect similar copying on the back face of the copy medium (this will hereinafter be called back-face copying and the course involved therefor will be called the back-face copying course). This system may be said to be the most practical one in that it involves only one set of copying processes identical with the single-face copying process, which leads to the provision of low-cost and compact copying machines.
The second feed means heretofore employed has been of the same type as the first feed means which is pre-loaded with copy mediums before the copying. It is such that sheets of copy medium are piled on a box-shaped feed table and separated from one another by separator means utilizing separator pawls or the like, and then advanced one by one by delivery means utilizing a rubber roller or a suction port. As such second feed means, there is known one which includes an arrangement of a cassette and a delivery roller.
However, when such second feed means is employed and copy mediums are to be automatically introduced thereinto, difficulties are encountered in properly piling the sheets of copy medium on the feed table and some device for arranging them in good order is required. The device would involve:
(1) Means for keeping the delivery roller retracted from its operative position while copy medium is being introduced, or means for keeping downwardly retracted from the feed table on which copy mediums are piled;
(2) Means for arranging the separator pawls at the opposite sides of the pile of copy mediums after introduced; and
(3) Means for aligning (relocating) the piled copy mediums with respect to their direction of movement and to the widthwise direction perpendicular thereto.
The heretofore proposed copying machines which have incorporated these devices have been very complicated in construction or insufficient in function. They have alsio been inconvenient in operability.